The present invention relates to engine oil change and maintenance monitors. More particularly, the invention relates to a vehicle engine oil change monitor for monitoring oil pressure at start-up to detect an oil filter change and for recording one or more parameters indicative of when the filter and oil was changed.
As is well known, internal combustion engine oil tends to degrade gradually with the passage of time and operation of a vehicle. The ability of an oil filter to remove contaminants from the engine oil deteriorates as the vehicle is operated. It is necessary to change the engine oil when the oil degrades to a certain unsuitable consistency and the functionality of the filters is impaired. Typically, the oil filter or filters are changed when the engine oil is changed.
Oil is typically changed on a periodic basis as needed. For example, oil may be changed at given intervals of time, given distances traveled by the vehicle, given duty cycles or given periods of time that the vehicle engine has run. If the oil and filter are not regularly changed, the resale value of the vehicle and durability of the engine are drastically reduced. The perception being that poor maintenance will result in reduced durability. Lessors of vehicles and owners of fleets of vehicles want to keep track of the date and mileage when the engine oil and filters are changed on their vehicles. In addition, lessors and fleet owners desire to make certain that the lessee or operator of the vehicle has the oil and filter changed at the required intervals. In the past there was no way of assuring oil and filters have been changed at required intervals, particularly when the vehicles or engines are out of the business""s full control.
Prior art oil change interval monitors have monitored the oil level in an oil pan to determine when oil has been changed. Oil level type monitors could determine that oil has been changed, but do not detect an oil filter change. A fleet owner using an oil level monitor could not be sure that the oil filters were changed when the oil was changed.
Oil filters can be changed without changing the engine oil. However, some oil in the head of the engine will typically leak out if the oil filters are changed without first draining the oil from the engine. For this reason, it is unlikely that oil filters will be changed without changing the oil as well.
Accordingly, there is a need for a passive engine oil change monitor which detects oil filter changes and records one or more parameters that indicate when the oil filter was changed. The oil change monitor of the present invention measures oil pressure at start up to determine whether an oil filter has been changed.
The present invention concerns a method and apparatus for enabling the determination of when an oil filter of a vehicle has been changed. The apparatus includes a sensor, a timer or counter, a comparator, and a recorder. The sensor monitors the oil pressure of an engine. The sensor includes an output for providing a pressure signal representative of the engine oil pressure. The timer or counter is in communication with the sensor. When a timer is used, it measures a time required to achieve a known oil pressure and provides a signal that represents the measured time. When a counter is used, it counts the number of engine revolutions or pulses that are required to achieve a known oil pressure and provides a counter signal that represents the number of counted revolutions or pulses. A comparator is coupled to the timer or counter. The comparator compares the measured time or counted number of revolutions required to achieve the known engine oil pressure to a known time or number of revolutions required to achieve the known pressure. The comparator has a comparator output that provides a comparator signal after an oil filter has been changed. A recorder is coupled to the comparator output. The recorder records data that indicates when the oil filter has been changed. Examples of recorded data include the odometer reading, or number of engine hours and the amount/quantity of fuel used (between filter changes).
In one embodiment, the apparatus includes both a timer and a counter. In this embodiment, a first comparator compares the measured time provided by the timer to a known time. The second comparator compares the number of revolutions counted by the counter to a known number of revolutions. In this embodiment, the recorder is coupled to the first and second comparators. The recorder records an odometer reading, quantity of fuel used, mileage or engine run time when both comparators or one of the comparators indicate that an oil filter has been changed. In one embodiment, the recorded parameters are communicated for service information.
The method of enabling the determination of when an oil filter of an engine has been changed comprises measuring a period of time or number of engine revolutions required to achieve a known engine oil pressure when the engine is started. The measured period of time or number of revolutions is compared to a known period of time or number of revolutions for achieving a known oil pressure. This comparison allows a determination to be made as to whether the oil has filter been changed since a previous start-up. When it is determined that the filter has been changed that event is recorded.
In one embodiment, the known period of time or known number of revolutions is the normal period of time or number of revolutions required to achieve a given oil pressure when the oil filter is full of oil when the engine is started. In a second embodiment, the known period of time or number of revolutions is the period of time or number of revolutions required to achieve a given oil pressure when the oil filter is initially empty when the engine is started. The odometer value, date, engine hours, fuel used, or global position are examples of parameters that may be recorded when it is determined that the oil filter has been changed. In one embodiment, an engine oil change is recorded when it is determined that the measured period of time or counted number of revolutions exceeds the known normal period of time or known number of revolutions.
An oil maintenance indicator constructed in accordance with the present invention detects an oil filter change without requiring the service person to perform any additional tasks when the oil and filter are changed. Not only does this type of maintenance indicator prevent oil and filter changes from going unrecorded, it also inhibits false records of oil maintenance from being created.
Additional features of the invention will become apparent and a fuller understanding obtained by reading the following detailed description in connection with the accompanying drawings.